Disposable liquid-absorbent article having longitudinal liquid barrier means, method and apparatus for its manufacture

ABSTRACT

A liquid-absorbent article to be worn by a user and comprising a substantially longitudinal absorption body (1) and a cover (2) enclosing the same. On a first side, facing the user in an in-use position, the cover displays a liquid pervious first cover-sheet (3) and on a second side, facing away from the user in an in-use position, the cover displays a second cover-sheet (4). On said first side is provided longitudinal liquid barrier means (17, 18) folded into tunnel shape, forming a channel (17&#39;, 18&#39;) with a longitudinal tunnel wall (17&#34;, 18&#34;). Said folded portions enclose longitudinal means (24, 25) with an elastically resilient supporting action acting in all directions transverse to the longitudinal direction of the article against the tunnel wall (17&#34;, 18&#34;) of the folded portion.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §§119 and/or 365 toSwedish Patent Application No. 9401681-3 filed on May 16, 1994 and PCTInternational Application No. PCT/SE95/00539 filed on May 15, 1995.

TECHNICAL FIELD

The present invention relates to a liquid-absorbent article.

The present invention also relates to a method and an apparatus for themanufacture of a liquid-absorbent article.

The present invention more particularly relates to articles providedwith leakage barriers primarily intended for use on sanitary towels, butthat of course may be used on other types of absorbent articles such asincontinence protection, diapers or similar.

Edge-leakage is a widespread problem primarily on sanitary towels, sincepatches of menstrual blood are difficult to remove and are experiencedas extremely embarrassing by the affected user. Sanitary towels, incontrast to diapers or the like, are fastened directly in the panties bythe user herself. Since both the size and shape of ladies panties varygreatly, it may easily happen that the positioning of the sanitary towelis less than optimal and varies from one time to another and betweendifferent users. An additional factor that increases the risk of leakageis that the sanitary towel is deformed during use, or moves away fromits original position in the panties. The negative effect of erroneouspositioning or deformation of the sanitary towel may to a certain extentbe alleviated by the provision of raised edge-leakage barriers on eachside of the longitudinal side-edges of the sanitary towel. Even if, byaccident, the sanitary towel has assumed such a position that it will bewetted near an edge-portion, the liquid may thereby be prevented frompouring out over the edge and giving rise to soiling of the user'sclothes.

Edge-leakage barriers are furthermore effective for controlling thespreading of liquid in the longitudinal direction of the sanitary towel.This is particularly useful in conjunction with the nowadays commonlyavailable, extremely thin sanitary towels which often have an absorptioncore with high liquid-spreading capacity. The drawback with suchabsorption cores, is that they usually spread out liquid equally well inall directions. Hereby, leakage arises as soon as the liquid reaches outto the side-edges of the sanitary towel.

BACKGROUND OF THE INVENTION

A number of different raised edge-leakage barriers are known in theprior art, see for example WO93/12795, showing edge-leakage barriers ona sanitary towel, which are formed by folded portions of the cover ofthe sanitary towel. An elastic cord, fastened and prestressed at eachend, extends along the inside of the formed folds and keeps the barrierraised in an in-use position. Ensuring a safe fastening of the ends ofthe cord means placing great demands upon the manufacture of thesanitary towels. Furthermore, the cord does not counteract sidewaysflattening. Additionally, transversal folds are formed by the action ofthe elastic cord in the barrier-wall, which may be experienced asuncomfortable by the user.

An additional problem with modern sanitary towels, are that the surfacematerial often consists of a perforated plastic layer, having favourablecharacteristics in terms of high liquid-permeability, high surfacedryness and little rewetting (i.e. small risk that liquid is pressedback out again through the layer). Such a material is experienced as"plasticky" by many users and therefore it has become common to providethe edge-portions of the sanitary towels with more "textile" strips ofnon-woven material (fibre cloth). An example of a document describingsuch "textile edges" is SE-B-900349D-1, which shows edge-portions withflat folds, yielding a very limited liquid-stopping effect.

SUMMARY OF THE INVENTION

The object with the present invention is to provide a liquid-absorbentarticle with an edge-leakage barrier, which by means of an integratedresilient action effectively counteracts squeeze in a direction ofheight as well as in a sideways direction.

Said object is achieved by a liquid-absorbent article according to thepresent invention.

Said object is also achieved by a method and an apparatus for themanufacture of a liquid-absorbent article.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in greater detail witha couple of embodiments with reference to the appended drawings, inwhich

FIG. 1 is a perspective view of a liquid-absorbent article according tothe invention in the shape of a sanitary towel,

FIG. 2 is a cross-section along the line II--II in FIG. 1, showing theedge-barriers with elastic means in a first embodiment,

FIG. 3 is a broken cross-section corresponding to FIG. 2, but withelastic means in a second embodiment,

FIG. 4 diagrammatically shows, in perspective view, an apparatus for themanufacture of an absorbent article according to the invention,

FIGS. 5 and 6 shows a folding device included in the invention,

FIG. 7 shows a perspective view of the folding device and a fold-overdevice according to the invention,

FIGS. 8 and 9 shows the fold-over device in a sideview and a topviewrespectively.

DESCRIPTION OF PREFERRED EMBODIMENTS

The sanitary towel shown in FIG. 1 and 2 generally comprises asubstantially longitudinal absorption-body for liquids and a cover 2enclosing the same. In the shown embodiment, the cover is provided witha liquid-pervious cover-sheet 3, which in an in-use position is facingthe user. The liquid-pervious sheet 3 suitably consists of anon-absorbent cloth or a perforated plastic film. The cover is alsoprovided with a preferably liquid-proof cover-sheet 4, for example madeof plastic film or a hydrophobed fibre cloth, said cover-sheet 4 facingaway from the user in an in-use position. In the shown embodiment, theliquid-pervious cover-sheet 3 extends over the central portion of thesanitary towel, over its entire length, but not over its width, whilethe liquid-proof cover-sheet 4 extends outside of the longitudinal edges5, 6 of the absorption body 1. In the shown embodiment, the cover isenclosed by two edge-strips 7, 8 of a skin-friendly "textile" materialof for example fibre cloth (non-woven) of a polymer, which along anouter edge-portion 9, 10 are joined with the liquid-proof sheet formingflange-like longitudinal edge-portions 11, 12 of the sanitary towel. Inthe shown embodiment, the longitudinal edge-portions are each providedwith a wing-like projection 11', 12', which by adhesive glue afterfolding over an edge of the panties may be fastened for fixing thesanitary towel. The joining between the different sheets in the cover 2is for example achieved by heating the material to a meltingtemperature, for instance by ultra-sound. In a similar fashion, theinner edge-portions 13, 14 of the edge-strips 7, 8 are joined with thelongitudinal edge-portions 15, 16 of the liquid-pervious cover-sheet 3.Instead of welding, i.e. melting the sheets together, gluing may ofcourse be used. Furthermore, the cover-sheet 3 may alternatively extendcompletely under the edge-strips 7, 8 and be directly joined to thesecond cover-sheet 4.

In order to form longitudinal edge-leakage barriers 17, 18, theedge-strips 7, 8 are folded-over in order to form a fully closedtunnel-shape enclosing a channel 17", 18", whereby the inneredge-portions 13, 14 are inserted between the liquid-pervious sheet 3and the underside of the edge-strips and are also joined to the same,for example by gluing or welding through the application of heat orultrasound. The tunnel shape may alternatively be formed solely by thecover-sheet 3 or by said sheet and the edge-strips 7, 8, which forexample may be folded into an omega-shape with the sheet 3 as abase-sheet. According to the invention, the folded-over edge-strips 7, 8are provided with elastic means or fill-in materials which in theembodiment shown in FIG. 2 comprise a strip 24, 25 folded into abellows-shape in cross-secton, and made for example of fibre cloth(non-woven) holding the edge-barriers in an upright position andcounteracting squeeze in a direction of height as well as in a sidewaysdirection.

According to the embodiment in FIG. 2, a combination of textile edgesand raised edge-leakage barriers has been achieved. The main componentis the folded material inside the outer channels. The folded materialshould be of a type having a certain built-in elastically resilientsupporting action in order to provide elastic support to the formedtunnel wall 17', 18'. Furthermore, the material should be substantiallyinsensitive to wetting so that it maintains its characteristics duringuse. The material hitherto tested is a thermobound non-woven material ofpolypropylene fibres. Whilst other types of fibres with relatively highbuilt-in resilient action are of course applicable, as are materialsthat have been treated (for example with a coating) so as to increasethe resilient action. Each strip 24, 25 is thus provided with one ormore longitudinal folds having a V- or Z-(zigzag) shaped cross-sectionwith a built-in pre-stress transverse the longitudinal direction of thestrips. The strips are fastened at their edge-portions 24', 24", 25',25"at least partially abutting the tunnel walls 17', 18'. In the shownembodiment, the folded strips 24, 25 are directed into an "upstanding"position so that they, by means of the pre-stressing, strive to rise upand support the tunnel walls 17', 18'even after a certain flattening,which may occur in a sales packaging. A highly resilient action is,however, achieved also in other transversal directions by the foldingand the built-in elastic deformation resistance of the material.

The barrier may, due to its design, stop or slow down the liquidspreading enough for the liquid to have time to be absorbed by anunderlying absorption body. The barrier may be more or lessliquid-proof, by being made of a liquid-proof or hydrophobic material.The folding of the material and the thickness of the barrier alsocontribute to the liquid-stopping effect. It is, however, nodisadvantage if the barrier is pervious to steam.

FIG. 3 shows the edge-leakage barrier 17 in a second embodiment, wherethe elastic means consists of a cord of for example foam material orfibre material, yielding a resilient action to the barriers in alldirections, seen in a cross-section, i.e. a transversal elasticity. Thecord may advantageously be pre-stretched, i.e. pre-stressed in thelongitudinal direction, into a transversal dimension below thetransversal dimension of the channel during manufacture, which afteroff-loading yields a dimensional increase in a transversal direction andthereby a mechanical locking against the tunnel wall and a pre-stressingin a transversal direction resulting in an increased resilient action.

Furthermore, the elastic means in both embodiments have both in commonthat they need not be fastened in the wall of the barrier, wherebyunnecessary tensions are avoided.

Referring to FIG. 4, a method and an apparatus will be described, forthe manufacture of the liquid-absorbent article according to theinvention. Hereby, the description is limited to the manufacture of theportion of the cover 2, which supports the edge-leakage barriers 17, 18.The rest, i.e. the manufacture of the absorption body, the liquid-proofsheet 4 and their joining together with the rest of the cover is knownin the prior art and should not require a closer explanation.

The apparatus according to FIG. 4 starts off from one and the samematerial line 20, continually rolled off a storage roll 21. Outeredge-cutting cutter-rollers 22, 23 are included in the apparatus forcutting out two outer edge-strips 24, 25 in order to form the filling orthe elastic means in the barriers. A centrally cutting cutter-roller 26divides the interstitial material line 27 into two parts 28, 29 to formthe edge-strips 7, 8 with the tunnel portions in the edge-leakagebarriers 17, 18.

The outer edge-strips 24, 25 are each fed to their own folding device30, 31 for folding the strips into a bellows-shaped cross-section, whichwill be described in greater detail below.

A fold-over device 32, 33 is also included in the apparatus for eachpart 28, 29 of the line, in which the barrier is formed by folding intoa tunnel shape with the folded strip inserted, which will be describedin greater detail below.

From a storage roll (not shown), a material line 34 is fed, which is toform the liquid-pervious cover-sheet 3. The completed edge-strips 7, 8with associated barriers 17, 18 are fed spaced apart a distance adaptedto the width of the material line 34, and joined together with the sameand is brought through a joining device 35 for joining of thefolded-over edge-strips 7, 8 with the longitudinal edges 47, 48 of thematerial line 34. The device 35, for example comprises a combinedheating- and embossing device, utilizing ultra-sound.

The folding devices 30, 31 in the shown embodiment, comprise, as is bestseen in FIGS. 5 and 6, two rotating rollers 36, 37 having zig-zag-shapedtracks 38, engaging each other. When the strips 24, 25 are fed throughthese rollers they are given the same shape as the profile of thetracks, i.e. a zig-zag-shape or a bellows-shape, after which the stripsare fed onto the fold-over devices 32, 33, see FIG. 7.

The fold-over device 32, in the embodiment shown in FIGS. 7, 8 and 9,comprises a fold-plate arrangement whose main part consists of agap-like longitudinal, outwardly open chute 39, extending substantiallytransversally (see the arrow 40) to the feeding direction 41.Furthermore, two redirection-edges 42, 43 situated asymmetrically in thehorizontal plane (the in-feed plane) is included, whilst the inlet ofthe chute 39 displays two, relative to the horizontal plane obliqueredirection-edges 44, 45.

By the edge-strip being drawn along the longitudinal direction of thechute 39, the folded-over portion of the edge-strip is formed. From FIG.7, it is apparent that the strip 24, folded into a bellows-shape, is fedsomewhat angled into the chute 39 from the folding device 30, wherebythe strip is guided and compressed towards the bottom 46 of the chute.Hereby, it is assured that the tunnel is subsequently closed without thefill-in material being trapped between the sealed sheets.

The invention is not limited to the embodiments described above andillustrated in the appended drawings, but may be varied within the scopeof the appended claims. For example, it is possible that theedge-leakage barriers are formed by folding of the cover-sheet 3 only.The strip 24, 30 25 may be twined instead of all in combination withfolding. The folding may also extend in a transversal direction. Thefolded strips may be laid at an angle to the surface of the cover sheeti.e. turned 90°, or obliquely, for example with a 45° inclination. Thebarriers may extend differently, they may for example extendtransversely along the longitudinal direction of the article or they mayextend curve-shaped. The barriers may be included in other articles forhygiene protection, for example diapers, incontinence protection,whereby the barriers may be designed with considerably largerdimensions.

We claim:
 1. A disposable liquid-absorbent article to be worn by a usersaid article comprising:a substantially longitudinal absorption body;and a cover enclosing the absorption body, the cover having a firstside, facing the user in an in-use position, which displays a liquidpervious first cover-sheet and a second side, facing away from the userin an in use position, which displays a second cover sheet, wherein saidfirst side is provided with at least one longitudinal liquid barriermeans including a portion formed by a material layer folded into atunnel shape such that said portion forms a channel with a longitudinaltunnel wall, wherein said portion folded into a tunnel-shape encloseslongitudinal elastic means with an elastically resilient supportingaction acting in all directions transverse to the longitudinal directionof the article against the tunnel wall of the folded portion: whereinsaid longitudinal elastic means in an unloaded condition displays atransversal dimension exceeding the transversal dimension of the channelbut in and for mechanical locking longitudinally against the tunnelwall.
 2. Article according to claim 1, wherein said longitudinal elasticmeans comprises a strip of material, folded along a longitudinal axisthereof.
 3. Article according to claim 1, wherein said longitudinalelastic means consists of fibre cloth.
 4. Article according to claim 1,wherein said longitudinal elastic means consists of an elastic strip offibre- or foam material.
 5. Article according to claim 2, furtherincluding two longitudinal edge-strips forming two edge-portions of thecover, wherein a longitudinal portion of said edge-strips forms saidtunnel-shaped portion.
 6. Method for the manufacture of a disposableliquid-absorbent article to be worn by a user, the article including asubstantially longitudinal absorption body and a cover enclosing thesame, the cover having a first side, facing the user in an in-useposition, which is provided by a liquid-pervious first cover-sheet and asecond side, facing away from the user in an in-use position, which isprovided with a second cover-sheet, whereby on said first side isarranged at least one longitudinal liquid-barrier means, formed byfolding a portion of material into a tunnel-shape, and thereby forming alongitudinally closed tunnel wall, said method comprising:holding thefolded-over portion open; inserting longitudinal elastic means, saidlongitudinal elastic means being pre-stressed into a reduced transversaldimension into the folded-over portion, folding the folded portion andgiving the folded portion said tunnel-shape enclosing said longitudinalelastic means, said longitudinal elastic means having, in an unloadcondition, a transversal dimension exceeding a transversal dimension ofa channel formed by the longitudinal closed tunnel wall for mechanicallocking longitudinally against the tunnel wall.
 7. Method according toclaim 6, wherein said longitudinal elastic means is formed by folding astrip of material.
 8. Method according to claim 7, wherein said strip ofmaterial is formed by cutting off an outer edge-portion of saidmaterial.
 9. Apparatus for the manufacture of a disposable article to beworn by a user, the article including a substantially longitudinalabsorption body and a cover enclosing the same, the cover having a firstside, facing the user in a in-use position, which is provided with asecond cover-sheet and a second side, facing away from the user in ain-use position, which is provided with a second cover-sheet, said firstside including at least one longitudinal liquid-barrier means, formed byfolding a portion of a material line into a tunnel-shape, forms alongitudinal closed tunnel wall, said apparatus comprising:a fold-overdevice for forming said folded-over portion into an open fold; devicesfor continually feeding said longitudinal elastic means beingprestressed into a reduced transversal dimension; and devices to sealthe fold into a tunnel-shape.
 10. Apparatus according to claim 9,further including a folding device for forming said longitudinal elasticmeans by longitudinally folding a strip of material.
 11. Apparatusaccording to claim 9, wherein the folding device comprises a fold-platearrangement with redirection-edges for redirection of the material linetowards an inlet to a gap-shaped, open chute.
 12. Apparatus according toclaim 9, further comprising outer edge-cutting means for cutting outouter edge-strips from said material line said edge-strips thus formingsaid longitudinal means.